Vacuum deaerator



y 28, 1953 H. L. BOWERS 3,091,098

VACUUM DEAERATOR Filed May 4, 1961 HERBERT L. Bows/25 INVEN TOR.

I I BY M7 ATI'OJ? EY United States Patent 6 York Filed May 4, 1961, Ser.No. 107,831 3 Claims. (Cl. 62-180) This invention relates to vacuumdeaeration, and it comprises, in combination, a deaeration tank, avacuum pump having an inlet connection in communication with said tank,a heat exchanger in said inlet connection, and means for circulatingrefrigerant through said heat exchanger, all as more fully described andas claimed hereinafter.

Vacuum deaerators have come into fairly extensive use for removingdissolved air and other gases from water in order to reduce thecorrosive effect of the water upon pipe lines and other metal objectswith which the water comes into contact. They are also used sometimes inthe treatment of boiler feed water. Vacuum deaerators are based upon thefact that the solubility of gases in water is zero at the boiling point.They operate by passing the water to be deaerated through a closedvessel in which the pressure is lowered by means of a vacuum pump to orclose to the value at which the water boils, such pressure depending, ofcourse, on the temperature of the water. The vacuum pump has the task ofnot only reducing the pressure in the vessel to the required low value,but also of removing from the low pressure condition in the vessel anddischarging into the atmosphere the gases released from the water,together with substantial quantities of water vapor formed byevaporation of a portion of the water passing through the vessel. Thisrequires a relatively large vacuum pump with relatively large powerrequirements. Both the high first cost of such large vacuum pumps, andespecially the high cost of power to operate them have prevented theinstallation of vacuum deaerators in many cases in which their use wouldotherwise have been desirable.

It is an object of this invention to provide a vacuum deaerator whichoperates effectively with a substantially smaller vacuum pump than hasheretofore been required.

Another object is to provide a vacuum deaerator with substantially lowerpower requirements for maintaining it in operation.

The manner in which these and other objects are achieved is set forth inthe following description and illustrated in the drawing which shows anelevational diagrammatic view, partly in cross section, of an apparatusin accordance with my invention.

My novel vacuum deaerator comprises a tank having in its upper portion aperforated plate 11 to distribute the water to be deaerated which isadmitted to the tank 10 through an inlet pipe 12. A chamber 13 is incommunication with the inside of tank 10 through connections 14 and 15.The pipe 12 passes through chamber 13 and is provided with a valve 16operated by a float 17 so as to maintain in tank 10 a water level asindicated by the symbol WL. An outlet pipe 18 provided with a valve 19is connected with the bottom of tank 10 and leads, usually through apump, to a point of use for deaerated water. Mounted on the top of tank10 is a compartment 20 which has a closed top 21 and an open bottom 22.A pipe 23 connects the upper portion of compartment 20 with a vacuumpump 24 discharging into the atmosphere. One or several ducts 26 aremounted on the plate 11 to establish inter-communication between thevapor spaces below and above the plate 11.

The compartment 20 may be partly within and partly without the tank 10as shown, or it may be arranged en- 3,091,098 Patented May 28, 1963tirely inside or entirely outside of the tank 10, if desired. The vacuumpump 24 may be a mechanical pump operated by an electric motor or asteam engine, or it may be a multi-stage ejector using steam as theoperating fluid.

As ancillary equipment for my deaerator, there are provided a compressor30, a condenser 31 located in the body of Water 25 below the water levelWL, and a heat exchanger or evaporator 32 located in the compartment 20.Conduit 33 connects the compressor 30 with the condenser 31, conduit 34interconnects the condenser 31 and the evaporator 32, and a conduit 35connects the evaporator 32 with the compressor 30. The system comprisingcompressor 30, condenser 31, evaporator 32 and conduits 33, 34, and 35is filled with a refrigerant 36, such as Freon, which is circulated inthe system by the compressor 30 to produce a cooling effect in theevaporator 32 and in chamber 20. A valve 37 is provided in conduit 34. Athermostatic element 38 in conduit 35 has an actuating connection 39with the valve 37 which is thereby adapted to throttle the flow of therefrigerant 36 so as to prevent the formation of any ice or frost on theevaporator 32.

The body of water 25 is a good place for the location of the condenser31 because then the heat extracted from the refrigerant 36 istransferred to the water being deaerated which is advantageous in manyinstallations. However, the condenser 31 may be placed in any otherdesired and suitable location.

In operation, the refrigeration mechanism is adjusted to maintain in thecompartment 20 a temperature of about 35 F., just enough above 32 F.,the freezing temperature of water, to insure that no ice formation willoccur. Let it be assumed that the water to be deaerated has atemperature of 60 F. At that temperature the water will boil under anabsolute pressure of 0.2563 pound per square inch. A vacuum pump 24 isselected to maintain in tank 10 an absolute pressure of about 0.26 to0.27 pound per square inch. As the entering water is distributed by theperforated plate 11 and drops through the vapor space below the plate 11practically all the dissolved gases are released, and together with asubstantial amount of vapor generated from the water by evaporation,rise through the ducts 26 and flow into the compartment 20. There thenon-condensable gases are cooled from about 60 F. to about 35 F. wherebytheir volume is reduced somewhat. At the same time the major portion ofthe water vapor is condensed, the water droplets falling through theopen bottom 22 back into the tank 10. The reduced volume ofnon-condensable gases mixed with the remaining reduced volume of vaporis then withdrawn by the vacuum pump 24 and discharged to theatmosphere.

Under these conditions the total volume of gases and vapor that must bewithdrawn by the vacuum pump 24 is only about one-half of what it wouldbe if no refrigeration were provided in the compartment 20. Accordingly,the size of the vacuum pump and the amount of power needed to operate itare reduced by about 50 percent. The cost of the refrigeration system aswell as its power requirements are substantially less than the aforesaidsavings effected in the vacuum pump so that the vacuum deaeratingapparatus, according to my invention, is less expensive, both in firstcost as well as in cost of operation, compared with a conventionalvacuum deaerator of the prior art.

Other incidental advantages of the new vacuum deaerator are that theheat from the water vapor condensed in compartment 20 is recovered, andthat the vacuum pump operates under more favorable conditions. When oilis used as sealing liquid the reduced volume of steam condensed in thevacuum pump has less tendency to emulsify and flood out the sealing oiland the problem due to the pump casing heating up is reduced becauseless steam is condensed and, therefore, less heat is generated in thepump.

While I have shown and described what I consider the best embodiment ofmy invention, modifications may be made without departing from itsspirit, andreference is, therefore, made to the following claims for adefinition of the scope of my invention. 1

What I claim is:

1. A vacuum deaerator comprising a tank, means for maintaining a waterlevel in said tank, an inlet for water to be deaerated cnonected withsaid tank, an outlet for deaerated Water connected with said tank belowsaid water level, a compartment located above said Water level andhaving its lower portion in communication with said tank,

a pipe connected with the upper portion of said compart- 15 ment, avacuum pump in said pipe, a condenser, an evaporator in saidcompartment, a compressor, a first conduit interconnecting saidcompressor and said condenser, a

second conduit interconnecting said condenser and said evaporator, and athird conduit interconnecting said evaporator and said compressor.

2. The vacuum deaerator of claim 1, said condenser being located in thelower portion of said tank.

3. In the vacuum deaerator of claim 1, a valve in said second conduit,and a temperature responsive element in said third conduit for actuatingsaid valve.

References Cited in the file of this patent UNITED STATES PATENTS1,466,670 Monti Sept. 4, 1923 2,613,513 Shields Oct. 14, 1952 2,671,524Gilwood' Mar. 9, 1954v FOREIGN PATENTS 427, 02 Great. Britain--V-.-l--Y-,-,-- .5

1. A VACUUM DEAERATOR COMPRISING A TANK, MEANS FOR MAINTAINING A WATERLEVEL IN SAID TANK, AN INLET FOR WATER TO BE DEAERATED CONNECTED WITHSAID TANK, AN OUTLET FOR DEAERATED WATER CONNECTED WITH SAID TANK BELOWSAID WATER LEVEL, A COMPARTMENT LOCATED ABOVE SAID WATER LEVEL ANDHAVING ITS LOWER PORTION IN COMMUNICATION WITH SAID TANK, A PIPECONNECTED WITH THE UPPER PORTIN OF SAID COMPARTMENT, A VACUUM PUMP INSAID PIPE, A CONDENSER, AN EVAPORATOR IN SAID COMPARTMENT, A COMPRESSOR,A FIRST CONDUIT INTERCONNECTING SAID COMPRESSOR AND SAID CONDENSER, ASECOND CONDUIT INTERCONNECTING SAID CONDENSER AND SAID EVAPORATOR, AND ATHIRD CONDUIT INTERCONNECTING SAID EVAPORATOR AND SAID COMPRESSOR.